title: Torsional deformation of double helix in interaction and aggregation of DNA.
abstract: We incorporate sequence-dependent twisting between adjacent base pairs and torsional elasticity of double helix into the theory of DNA-DNA interaction. The results show that pairing and counterion-induced-aggregation of nonhomologous DNA are accompanied by considerable torsional deformation. The deformation tunes negatively charged phosphate strands and positively charged grooves on opposing molecules to stay "in register", substantially reducing nonideality of the helical structure of DNA. Its cost, however, makes interaction between nonhomologous DNA less energetically favorable. In particular, interaction between double helical DNA may result in sequence homology recognition and selective pairing of homologous fragments containing more than 100-200 base pairs. We also find a weak, but potentially measurable, increase in the expected counterion concentration required for aggregation of nonhomologous DNA and slightly higher solubility of such DNA above the critical concentration.
authors.affiliation: Institut für Festkörperforschung (IFF), Forschungszentrum Jülich, D-52425 Jülich, Germany, Department of Chemistry, Faculty of Physical Sciences, Imperial College London SW7 2AY, U.K., and National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892.
authors.forename: A G
authors.initials: AG
authors.lastname: Cherstvy
authors.forename: A A
authors.initials: AA
authors.lastname: Kornyshev
authors.forename: S
authors.initials: S
authors.lastname: Leikin